Method for killing meristematic buds

ABSTRACT

SULFITE ESTERS OF THE FOLLOWING GENERAL FORMULA ARE USED AS CHEMICAL PRUNING AGENTS:   R-O-SO-O-R&#39;&#39;   WHEREIN R IS AN ALKYL OR HALOALKYL GROUP HAVING 1 TO 18 CARBON ATOMS AND R&#39;&#39; IS A CARBOALKOXYALKYL OR ACRYLOXYALKYL GROUP OR A HALO SUBSTITUTED DERIVATIVE THEREOF HAVING FROM 3 TO 9 CARBON ATOMS.

United States Patent Oflice 3,690,861 Patented Sept. 12, 1972 ABSTRACT OF THE DISCLOSURE Sulfite esters of the following general formula are used as chemical pruning agents:

R-O- -OR' wherein R is an alkyl or haloallcyl group having 1 to 18 carbon atoms and R is a carboalkoxyalkyl or acryloxyalkyl group or a halo substituted derivative thereof having from 3 to 9 carbon atoms.

This is a division of application Ser. No. 693,117, filed Dec. 26, 1967, now U.S. Pat. 3,578,694.

This invention relates to sulfite diesters having an alkyl or haloalkyl group and a carbalkoxyalkyl or acyloxyalkyl group and their biological uses.

The compounds of the invention have the formula:

0 R-O-i'l-O-R' where R is an alkyl or haloalkyl group having from 1 to 18 carbon atoms, and R is carbalkoxyalkyl or acyloxyalkyl group having from 3 to 9 carbon atoms or their halosubstituted derivatives.

Examples of R are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec.-butyl, tert.-butyl, amyl, hexyl, 2-ethylhexyl, heptyl, octyl, nonyl, decyl, isodecyl, undecyl, dodecyl, hexadecyl, octadecyl, 2-chloroethyl, 3-chlorobutyl.

Examples of R are carbomethoxymethyl, carboethoxymethyl, carbopropoxymethyl, carbobutoxymethyl, carbethoxyethyl, carbethoxybutyl, carbethoxychlorobutyl, 3- carbobutoxy 2 hexyl, acetoxyethyl, propionyloxyethyl, butyryloxyethyl, 2-acetoxypropyl, 3-acetoxy-2-butyl, acetoxychlorobutyl.

The preparation of the chemicals of the invention may be carried out by reacting a hydroxyester with the separately prepared chlorosulfinate of an alcohol, which may be made by reacting the alcohol with thionyl chloride. Such preparation is illustrated by the following reactions with the same symbols R, R as in the above general formula.

II ROH S0012 R-O SCI H01 The first reaction is carried out at a temperature of between 5 C. and 30 0., preferably about 0 C., and the yield of chlorosulfinate is nearly quantitative. An inert solvent such as benzene, xylene or solvent naphtha may be used, but is generally unnecesary. The second reaction is carried out in the presence of an HCl acceptor, such as pyridine, dimethylaniline or trimethylamine, and in a solvent such as benzene, xylene, or solvent naphtha. The reaction temperature is generally between 10 C. and 50 0., preferably about 0 C.

Compounds of this invention may be prepared by the usual methods of esterification. Two examples are shown below.

EXAMPLE I Preparation of l-carbethoxyethyl octyl sulfite To 910 g. (7.0 moles) n-octyl alcohol cooled to 5-10 was added dropwise with stirring 635 ml. (1040 g., 8.75 moles) thionyl chloride keeping a maximum reaction temperature of 25. The mixture was allowed to stand 16 hours and then the dissolved HCl was removed with an aspirator. Further stripping of the chlorosulfinate was carried out to 25 (3 mm.) by means of a vacuum pump. The yield is nearly quantitative and the material is of suificient quality to be reacted directly in the next step.

To a cooled solution of 21.2 g. (0.1 mole) n-octyl chlorosulfinate in 25 ml. benzene was added a solution of 13.0 g. (0.11 mole) ethyl lactate and 8.1 ml. (7.9 g., 0.1 mole) pyridine in 25 ml. benzene keeping the reaction temperature below 10. The mixture was stirred for 20 minutes and then was washed with 25 ml. water, 25. ml. 2 N NaOH and twice with 25 ml. saturated salt solution. The organic layer was dried and the solvent was removed under reduced pressure. The product was distilled, B.P. 140-147 (1.8 mm.), yield 20.6 g.

Analysis.-Calcd. for C H O S (percent): S, 10.89. Found (percent): S, 11.21.

An alternative method for preparing some of the compounds of the invention involves reacting a chlorosulfinate with an epoxide. This is a very straight-forward reaction giving nearly quantitative yields of pure product. However, in cases where the oxide is unsymmetrical, two isomers may be obtained depending on how the oxide ring opens. This is illustrated by the following reaction:

0 O RO C1+Cfi- CH -r C a COOOzHu O O CH: ROQOCH-CHOl-l-ROQOCH-(BHGI Ha COOCzH COOCQH;

The following example illustrates the preparation of a sulfite by this method.

EXAMPLE II Preparation of 2-carbethoxy-2-chloro-Z-propyl-Z-chloroethyl sulfite (and isomer) The preparation of 2-chloroethyl chlorosulfinate is well known in the literature, e.g., U.S. 2,529,494 and 2,529,- 493.

To a solution of 16.3 g. (0.1 mole) 2-chloroethyl chlorosulfinate in 25 ml. ether was added 13.7 g. (0.105 mole) ethyl 2,3-epoxybutyrate in 25 ml. ether, while maintaining the reaction temperature at about The mixture was stirred for minutes and the ether and excess epoxybutyrate were removed under vacuum of 0.5 mm. Yield 29.2 g. (99% Analysis. Calcd. for C H Cl O S (percent): S, 10.93. Found (percent): S, 10.99.

The last two compounds shown in Table I were prepared by this method.

Sulfur analyses of other chemicals of the present invention are shown in Table I.

TABLE I Sulfur analysis Calcd. Found Carbethoxymethyl n-hexyl sulfite 12. 70 12. 26 Carbetoxymethyl n-octyl sulfitc. 11. 43 11. 99 Carbcthoxymethyl n-decyl sulfite 10. 52 10.05 Cnrbethoxymethyl Z-ethylhexyl sulfite 11. 43 11. Carbethoxymethyl tridecyl sulfite 9. 15 9. 08 Carbomethoxyrnethyl n-octyl sulfite 12.05 11.89 l-carbethoxyethyl n-octyl sulfite 10.89 11. 21 l-carbobutoxyethyl n-deeyl sulfite 9. 12 9. 38 l-carbobutoxyethyl tridecyl sulfito 8.14 8. 28 2-acetoxyethyl ndecyl sulfite 10.39 10. 08 2-acetoxyethyl tridecyl sulfite 9. 15 9. 18 2-acetoxyethyl n-octyl sulfite 11. 43 11. 52 2-acetoxyethyl 2-oetyl sulfite..- 11. 43 10. 71

l-earbethoxy-l-chloro-2-propyl hexyl sulfite and isomer 10. 20 9. 46

2-chloro-10 carbomethoxydecy1 2-chloroethyl sultite and isomer- 8. 49 8. 49

In accordance with this invention it has been discovered that sulfites derived from hydroxy esters have outstanding chemical activity with regard to killing meristematic buds.

They may be used for killing meristematic buds on ornamental and agriculture herbaceous, semi-woody and woody plants such as chrysanthemum, cotton, azalea, apple and tobacco. Moristematic buds include both terminal and auxiliary buds. The selective killing of terminal buds is an application for which the chemicals of the invention are particularly useful.

Additionally, the compounds of the invention are useful as insecticides and nematocides.

For the several biological uses, the compounds of the present invention may be applied to plants, which term includes various plant parts such as seeds, flowers, fruits, vegetables, roots and foliage in various manners. Seeds may be treated directly with the chemical before planting, or seeds may be treated with the chemical by incorporating the chemical in the soil before or after planting the seeds. The chemicals may be applied to plants in an inert medium as a dust in admixture with a powdered solid carrier, such as the various mineral silicates, e.g., mica, talc, pyrophyllite and clays or as an aqueous composition. The chemicals may be applied in admixture with small amounts of surface-active wetting agents, which may be anionic, non-ionic, or cationic surface-active agents, generally as aqueous compositions. The chemicals may be dissolved in organic solvents such as acetone, benzene, or kerosene, and the solutions of the chemicals emulsified in water with the aid of surface-active agents. Such surface-active agents are well known and reference is made to US. Pat. No. 2,547,724, columns 3 and 4, for detailed examples of the same. The chemicals of the invention may be admixed with powdered solid carriers, such as mineral silicates, together with a surface-active agent so that a wettable powder may be obtained which may be applied directly to plants, or which may be shaken up with water for application to the plants in that form.

The concentration of active chemical in the useful chemical pruning formulations may vary widely, e.g., from 1% to 95 Generally, the active chemical in dispersions which are applied are from 0.05% to 6.0%. The amount per acre of active chemical applied may vary from 0.5 pound to 50 pounds depending on the plant being treated and other factors known to those skilled in the art.

Where the compounds are used as insecticides the concentration of active ingredient in the formulation ranges from 1 to 95%. Generally the dispersion which is applied has from 0.001 to active chemical. The application rate is 0.1 to 25 lbs. per acre of active chemical.

For nematicide application, formulations generally contain 0.001 to of active chemical and the dispersions which are applied have from 0.001 to 4.0%. Here the application rate ranges from 0.1 to 25 lbs./

acre.

The following example illustrates the use of the compounds of the invention for killing meristematic buds.

EXAMPLE III Rooted cuttings of Chrysanthemum morifolium cv. Improved Indianapolis Yellow are planted in 12 oz. Styrofoam pots in a sterilized soil mixture of one part soil, one part peat moss, and one part horticultural perlite. At planting and weekly thereafter, the plants are fertilized with 25-5-30 analysis fertilizer at the rate of one ounce per three gallons of water. For seven to ten days following planting, the plants are placed under a polyethylene tent and frequently syringed to provide conditions of both high temperature and high relative humidity, respectively. The potted plants are maintained under longday conditions by the use of supplemental fluorescent light from five pm. to nine p.m. and from five am. to seven a.m. daily. Ten days to two weeks after planting the established plants are ready to treat.

Two and one-half grams of the selected compound and 0.23 gram of isoctyl phenyl polyethoxy ethanol are combined to produce an emulsifiable concentrate, 90% of which is the active ingredient. Enough water is added to the 2.83 grams of emulsifiable concentrate to bring the total volume to ml. This results in a 25,000 p.p.m. solution. Dilutions to 10,000, 4000 and 2000 p.p.m. are prepared by diluting the appropriate amount of the 25 ,000 p.p.m. solution with water to which isooctyl phenyl polyethoxy ethanol has been added at the rate of two drops per 100 ml.

The aqueous formulations are applied as a foliar spray until the plants are wet to run-off. The plants are allowed to dry and then placed in the greenhouse at a temperature of 65 F. minimum night temperature.

Within 12 to 24 hours following the application of optimum dosages and formulations of said compounds, the shoot apex, embryonic leaves and embryonic axillary meristems (hereinafter collectively referred to as the terminal meristem) turn black and are very flaccid. Within the next few days this same dead tissue turns grayish and a constriction appears on the stem at the proximal limit of the killed tissue. At optimum concentrations the compounds are non-phytotoxic to matured axillary meristems, leaves, and stem tissue. This process of killing the terminal meristem with aqueous emulsions of the compounds of the mentioned type will hereinafter be referred to as chemical pruning.

At concentrations less than optimum the terminal meristem is not completely killed and therefore maintains apical dominance over the axillary meristems. At concentrations in excess of optimum both the terminal and axillary meristems may be killed without causing damage to foliage and stem tissue.

With other compounds, concentrations in excess of optimum may kill the terminal meristem and be phytotoxic to mature leaves but may not kill the axillary meristems. Concentrations in excess of optimum of still other compounds may kill the terminal and axillary meristems and be phytotoxic to the mature leaves.

The followingtableshows the minimum concentration of the compounds required to achieve chemical pruning activity.

The activity of the chemicals of the present invention as insecticides is shown in the following example.

EXAMPLE IV In the mosquito larvae test, mg. of chemical is dissolved in 1 ml. of acetone and diluted to 100 ml. with tap water to give a 100 p.p.m. solution. Dilution to 10 p.p.m. is made with tap water. Twenty five ml. aliquots of each dosage, replicated once, are placed in test tubes and ten 4th instar larvae of Aedes aegypti are added and the tubes are held at 70 F. in darkness for 72 hours. At the end of this period the live and dead are counted and percent control calculated.

In the mite contact test, 400mg. of chemical is dissolved in 10 ml. of acetone and two drops of Triton X-l00. This is then diluted to 200 ml. with distilled water to give a concentration of 2000 p.p.m. Four-week-old cotton seedlings grown in 12 oz. Styrofoam cups are used as the host plants. A quarter sized circle of tanglefoot is placed on both primary leaves of each cotton plant in order to confine the mites to the upper leaf surface. Approximately 24 hours prior to spraying with said chemicals, about ten two-spotted spider mites, Tetranychus urticae, are placed inside each circle. Plants are sprayed to runofi with the 2000 p.p.m. solution, using a concentrate sprayer which is positioned 6 to 12" from the plants. One plant (2 leaves) is used in each pot for one replicate. Two replicates are used for each chemical tested. Initial counts of the mites present are made shortly after spraying. The plants are held five days in the greenhouse, at which time a final count is made of the live mites remaining Abbotts formula:

Percent control= Percent mites living (untreated) --peroent mites living (treated) EXAMPLE V Three hundred milligrams chemical is dissolved in 10 ml. of acetone. Ninety milligrams (three drops from a standard medicine dropper) of this 3.0% solution is added to a BPI standard water glass containing 150 mg. of a 0.01% solution of Triton X-100 (five drops) in distilled water. Thirty milligrams (1 drop) of a nematode suspension containing -100 live Panagrellus redivivus nematodes is added to the watch glass containing the chemical preparation. The final concentration of chemical in the BPI watch glass is 1.0% (10,00 p.p.m.). The test is conducted in duplicate using a dilution series. An untreated check, i.e., two watch glasses containing 0.01% Triton X-l00 solution and nematodes but no chemical, is included in the test. The watch glasses are placed in 100 x 15 mm. inverted Petri plates and sealed with water to avoid evaporation. The test is kept in the laboratory at room temperature. The results are taken by microscopic inspection of the nematodes in the watch glasses. They are recorded as precent nematode control by contact after 48 hours.

Table IV shows the nematocidal activity of several alkyl carbalkoxyalkyl and alkyl acyloxyalkyl sulfites:

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

1. A composition for killing meristematic buds on ornamental and agricultural herbaceous, semi-woody and woody plants which comprises a compound having the formula:

wherein R is an alkyl or a monhaloal'kyl group having 1 to 12 carbon atoms, and R is a carbalkoxyalkyl or an alkanoyloxyalkyl group or a monohalo-substituted derivative thereof having 3 to 9 carbon atoms, and the total carbon atom content of said compound does not exceed 20, and a surface active agent.

2. The composition of claim 1 wherein R has up to 12 carbon atoms.

Percent mites living (untreated) Table III shows the activity of the alkyl carbalkoxyalkyl and alkyl acyloxyalkyl sulfites:

3. The composition of claim 1 wherein R is carboxyethyl.

The nematocidal activity of the compounds is shown in the following example.

4. The composition of claim 1 wherein R' is acetoxyethyl.

5. The composition of claim 1 wherein the compound 1 lstooctyl phenyl polyethoxy ethanol surface active wetting is carbethoxymethyl octyl sulfite, Men S.

6. The composition of claim 1 wherein the compound is carbomethoxymethyl octyl sulfite.

7. The composition of claim 1 wherein the compound is carbethoxyethyl octyl sulfite.

8. The composition of claim 1 wherein the compound is 2-acetoxyethyl octyl sulfite.

9. The composition of claim 1 wherein the compound is l-carbethoxy- 1-ch1oro-2-propyl hexyl sulfite.

10. A method for killing meristematic buds on ornamental and agricultural herbaceous, semi-woody and woody plants which comprises treating the buds with a compound of the formula:

rr-o-g-o-n" wherein R is an alkyl or a monohaloalkyl group having 1 to 12 carbon atoms, and R is a carbalkoxyalkyl or an References Cited UNITED STATES PATENTS 2/1971 Covey et al. 71-103 JAMES'O. THOMAS, JRQPrimary Examiner US. 01. X.R. 

